Desulfurizing hydrocarbon oils



Aug- 22; 1950 D. A. MGCAULAY ETAL 2,519,587

DESULFURIZING HYDROCARBON OILS Filed June 18, 1947 2 sheets-sheet 1 x ifn STRlPP/A/G ZONE 34 `S21/fur Compounds Aug 22,1950 D. A. MGCAULAY ETAL2,519,587

DESULFURIZING HYDROCARBON OILS 2 sheets-sheet 2 Filed June 18, 1947Patented Aug. 22, 195o l DESULFURIZINGv HYDRlOCARBON OILS Davia A.Macaulay, chicago, 111., and Arthur P.

Lien, Hammond, Ind., assignors to Standard Oil Company, Chicagoylll., acorporation of Indiana Application June1s,1947,seria1N0.'z55,45'z

This invention relates to a process for desulfurizing hydrocarbon oilslMore particularly it relates to a process Vfor the desulfurization oflhydrocarbon oils containing hydrocarbon disuldes.

In ther petroleum industry a number ofnhydro` carbonoils are producedwhich comprise sulfur compounds, l including hydrocarbon disuldes.Particularly, the petroleum industry normally produces relatively lightor low boiling hydrocarbon oils such as gasoline,naphtha, kerosene andheater oils which contain hydrocarbon disulfides. Thus, for example,mercaptan-containing (sour) gasoline condensed from natural gas,distilled from crude petroleum oils orY derived from petroleum oilfractions bycracking operations is ordinarily subjected to so-calledsweetening operations in the course of which the mercaptans in thegasoline are converted to gasoline-soluble disuldes which are retainedin the gasoline. Although hydrocarbon disuliides do not possess the foulodor of alkyl mercaptans, they markedly reduce the ability of leadalkyls such Aas leadv tetraethyl to increase the octanenumber of thegasoline or naphtha in which theyare present, i. e., they reduce theVlead susceptibility of the. fuel.r It has been observed that of thevarious types of sulfur compounds, hydrocarbon disuldes appear to exertthe greatest depressing eiiectA on lead susceptibility (W. A. Schulzeand A. Buell, National Petroleum News, 27, No. 41, page 25V (October 9,11935.) Hydrocarbon disuldes are also undesirable componentsinhydrocarbon oils intended for ,use as `fuels 4for the reason @that in,the combustion process they are converted to sulfur vdioxide which,with the water'genera'ted in the combustionof hydrocarbons, tends 'dtocause corrosion of metal surfaces with'which it comes in contact.

Accordingly, it is an object of our invention to provide a process fordesulfurizing hydrocarbon oils comprising sulfur `.compounds includinghydrocarbon disuldes. Y 'Another object ofv our invention is to providea process for converting hydrocarbon disyuldes and oleiins contained inhydrocarbon oilsintovaluable chemical products which can be recoveredOr'empIOyment in in-v dustry; An additional object is to provide aprocess for Vremoving hydrocarbon disulfides and equimol'ecula'r amountsof olnic hydrocarbons from-hydrocarbon oils containing them, e. g.,gasolinev or kerosene.` A further Objectis to provide a methodiforremoving hydrocarbon disulfides and otherHsulfur 'corripounds4 fromlight Claims. (Cl. 196--31) hydrocarbon oils without substantially removing low boiling mononuclear aromatic hydrocarbons which possess highoctane number.

Onel more object of our invention is to provide a process for removinghydrocarbon disuliides from a hydrocarbon oil containing substantiallyno olenic hydrocarbons or containing an olefinicV hydrocarbon in lessthan an equirnolar amount based on its content of hydrocarbon disuldes;Still another object is to` provide a method of simultaneously.alkylating aromatic hydrocarbons contained in a light hydrocarbon oilwith olelins and effecting the conversion of. hydrocarbon disuliides andother sulfur compounds contained therein to compounds which arepreferentially soluble in liquid hydrogen ilu'- oride andare extractedfrom said oils by said liquid hydrogen fluoride, whereby both the clearoctane number and lead susceptibility of the light hydrocarbon oil areimproved. These and other objects of our invention will become apparentfrom the ensuing description thereof read in conjunction with theaccompanyl ing figures.

We have observed that hydrocarbon disuldes are dissolved only to alimited extent by concentrated liquid hydrogen fluoride at normaltemperatures'. However, we have discovered that hydrocarbondisuliidescontained in a hydrocarbon oil can be reacted with olenic hydro-Jcarbons in the presence of concentrated liquid hydrogen fluoride toproduce reaction products which appear to be almost entirelydi-thioethers and which are extremely soluble inr concentratedhydrofiuoric acid at normal temperatures. Thus,- We have discovered adesuliurization process for' the removal of hydrocarbon disuldes fromhydrocarbon oils in which process concentrated liquid hydrogenfluoridefunctions both as a catalyst'and as a solvent for thesulfur-containing reaction products,'i. e. as a desulfurizing agent forthe hydrocarbon oil. 'The reaction which appears to take place may berepresented as follows Y i R1 R1 Rl Rl R-s-s-R+R'1=af R-s-(lJ-J-s-R A l'if wherein each R represents a hydrocarbon radical (usually an alkylradical) and each R' may be hydrogen or a hydrocarbon radical. Although.our invention may be applied tothe desulfurizaton of any hydrocarbon oilcontaining disuldes, it is believed thatits application will be ofprincipal interest for the desulfuriaation of relatively low boilinghydrocarbon oils such as gasoline-s, naphthas, kerosenes. Our inventionmay, however, be applied advantageously to furnace oil and the like.

Light hydrocarbon oils obtained from sour crudes contain a variety ofalkyl mercaptans, including methyl, ethyl', nand iso-propyl, nandiso-butyl, nand iso-amyl mercaptans and smaller amounts of higher alkylmercaptans such as hexyl, heptyl and octyl mercaptans. In the'sweetening process these rnercaptans are converted to symmetrical andunsymm'etrical alkyl disuldes.

In addition to hydrocarbon disulfides the hy' drocarbon oil to betreated may containaromatic hydrocarbons, particularly relatively 10Wboiling mononuclear aromatic hydrocarbfvmsfv such as benzene, toluene,Xylenes, ethylbenzene, ethyltoluene, propylbenzene or butylbenzenes,and" mono-olenic hydrocarbons, in addition to the saturated.hydrocarbons; surprisingly, thesel aromaticsare' soluble only to avery;minor extentv irr liquid hydrogen;k iiuorid'e.` at ambient tempera.-

tures. Thus, gasolinas produced by thermal cracking'of gascoils or otherhigh'b'oilfing frac-- tions of. crude oil: which. have been sweetened.by some conventional process such as doctor sweetening, or bycopper-salts adsorbed on clays, contain hydrocarbon. dis-ulldes, olens:and usu-` allyr-v some aromatic hydrocarbons such as ben'- zene,toluene. and the'v like: Concentrated. sulfuri'c acid, e. g. 90' to 98Weight. per cent sulfuric acid, in theY absence` of' olefins, convertsmercaptane-'in'. hydrocarbon cils to disuldes1 and extractsa'fp'ortiori. of the disuldes. Gasolines derivedfr byY condensation fromsoury natural gas or. by non-cracking; distillation-. url crudepetroleum, followed bya svveeten-ingi operation, con.- tairrhydroca-rbondisulfides" but little? or. no ole#- n'icf hydrocarbons..

In applying our invention to hydrocarbon charging stocks; containingdisulfides: but noL ole.- nic. hydrocarbons; or less. than arr.equimolar' amount of olenic hydrocarbons basedonthe` disulde'content of:the charging stock, it will be necessary to treat thel charging stockAwith: concentratedffliquid. hydro-gen uoride and arri added olen inquantity such that the: total olen. available for reactionzwith: thevhydrocarbon disulfide' is'atwleast equ'imolar with; respect to the:disulfide. Thus" in desuliurizing straight: run, sweetened gasoline orkerosene it is necessary to reactv the' charging' stockV with addediolefin. in:Y an amount equimolar with' the amount of hydrocarbondisuldecontained in? the. stools. When the' amount of mono-oleriichydrocarbonscontainedinl the charging stock exceeds thehydrocarbon disulfide contentof the stock, .the treatingcon'- ditions may beadjusted (by control ofther amount' of hydrogen iluoride, temperature and time) to effect the.disuli'ide-olen` reactionand extraction. describedfabove without causingsubstantial polymerization or other react-ion ofthe olefinichydrocarbons present in the charging stock in. excess of the amount ofhydrocarbon di- A` Wide variety of mono-olenichydrocarbons may be" addedto the disulde-containing chargingstocks ltovr adjust the'disuliid'e:olefin mole ratio` to about 1. Either individual. olefinsor mixtures ofolensmay bei employed'. Mixtures ofolens with saturated` hydrocarbons,e. g. as found-in petroleum reinery fractions,` may likewise beemployed.

Thusf the invention may be' practiced-v with tetra-isobutylenes;

4 acyclic mono-olenic hydrocarbons, such as ethylene, propylene, 1- or2-butene, isobutylene, pentenes, hexenes, decenes, dodecenes, cetenes,styrene, vinylacetylene, alpha-alkyl styrenes such as alpha-methylstyrene, alphaor beta-vinylnaphthalenes; polymers of the above andsimilar olens, for example diisobutylene whichy is a mixture of2,4,`4,-trimethyl-1- and 2-pentenes, propylene or isobutylene trimersand tetramers, and the like. The olenic polymer employed may bedepolymerizable under the reaction conditions to yieldithe monomericolefin which Will then enter intoreaction With. the' hydrocarbondisulde.

We) may also employ cyclo-oleflns, e. g., cyclohexene, methylcyclohexenes, cyclopentene, methylcyclopentenes, terpenes,3-vinylcyclohexene., cyclohexadiene-1,3, p-benzoquinone.

Poly-olens may also be employed in this inventi'on; for exampleLS-butadiene, isoprene, 2,3- dimethyl-LIE-butadiene,` cyclopentadiene,dicyclopentadiene'; l.,4-pentadiene,. L-hexadi'ene, divnylbenzene andthe like? Wemay al'soemploy a. variety of substituted oleflns in. thepracticevoi'. this invention, for example dichlorostyrenes,trifluoromethylvinylbenxzeries;v vinyl heteriocycliccompounds such asvinylthioplienesg. vinylfuranes and vinylp'yridines'; methyl'vin'ylketone', vinyl acetate, esters of vcr'otonic,acrylic, metliacrylic orsorbic acids',v etc;

The process of the present inventionmay beI practiced not only withol'en'ic compounds but' also with materials'capable of yielding thesecompounds under certain reaction conditions. Thus, ashas been pointedout above, depolymerizable polymers may beemployed asa source of`oleiinV monomer for the" reaction with a disuld'e: Examples of suchpolymers are' di, trior In the presencel of acidic condensation'catalysts certainV highly branched chain paraf'linic hydrocarbonsundergo cleavage tof'yield olenichydrocarbons.. and may be employed as asource of olens for the 4present invention; a suitablel example ofsuch'a highly branched chain paraffin hydrocarbon is commercial isooctanewhich comprises predominantly 2,2,4-trimethylpentane. Cycloalkanes ofhighly strained ringstructuresuch as cyclopropane and substitutedcyclopronanes. c.` g.. methylor ethylcyclopropane, can function as` asource of propylene or substituted propylenesy in the presence ofacidicI condensationcatalysts.

Certain derivatives of olenhydrocarbons are unstable in. the presence ofacidic condensation. catalysts and are capable of yielding olensintheirpresence. This isespecially true of derivatives`V of tertiaryv olens.These derivatives comprise mercaptans, alcohols, ethers, halides and thelike. Examples are tert.butylmercaptan, ethanol, isopropanol,tert-butanol, 4di-tertfbutyl ether, tertiary octylchlorides,tert-methylcyclopentyl chloride, tertQ-butylchloride,`tert-amyl chloride.

We prefer to carry out tbe process of our invention` with commercial,liquid, substantially anhydroushydrogenfluoride. However, the inclusionof relatively -small amounts of WaterV inV the solvent-catalyst may betolerated; thus the liquid hydrogen uoridef solvent-catalystV maycontain up to' about l0 Weight per cent of Water. In general, vvatervtends to reduce theV solvent capacity of hydrogen: fluoride for Sulfurcompounds; therefore,v we prefer to employ substantially anhydrousliquid hydrogen. fluoride or s: hydrogen fluoride containing ino morethan about 5 weight per cent of water. l. .l The amount of hydrogenfluoride employed will varyf .somewhat with the particular chargingstock, temperature, other operating. conditions andthe results sought.`However, we ordinarily employ atleast sufficient hydrogen fluoride to iform a distinct acid phase, i. e., a phasein which liquid hydrogenfluoride is the predominant component. We may employ 5 to 100 per centof commercial liquid hydrogen fluoride or even more,v based on thevolume of the hydrocarbon charge stock; ordinarily we employ betweenvabout l0 and about 30 volume per cent of liquid hydrogen fluoride basedon the volume of the hydrocarbon charging stock.

It 'may sometimes be desirable 'to effectreaction of hydrocarbondisulfldeswith olefins and extractionof'the reaction products,respectively, in twodistinct stages. In` the first stageithe'reactionbetween a hydrocarbon disulfide and an olefln'maybe effected in thepresence of a small, catalytic amount of concentrated vhydrogen fluorideinsufficient to function efficiently as a solvent for the reactionproducts;A for example, the reaction may be effected with between about116 and about 5 volume per cent of liquid hydrogen fluoride based on theVolume of the hydrocarbon charging stock.` When hydrogen fluoride isemployed as a catalyst only it is preferred to employ an'A amount atleast equimolar withrespect to the "amount of hydrocarbon disulfidejcontained in the hydrocarbon charging stock. In the second (extraction)`stage, additional concentrated liquid hydrogen fluoride is added to thereaction mixture derived from the flrst stage in an amount suflicient atleast to form a distinct acid phase. The acidphase contains thesu1fur`"ontaining reaction products,l predominantly d thioethers.When-reaction and `extraction ar ffected as distinct operations it maybe desired'g-to conduct each `operation at a different temperature. Thusreactionmay be effected at normalor elevated temperatures, for example,temperatures from about 50 F. to as high as about 250.*s F. andextraction may be effected at normal or reduced temperatures, forexample, temperatures from 100'.F. down to 0 F. or even lower; forexample Where olefin addition is necessary, the olefin may be addedbefore, during or afterv the addition of the hydrogen fluoride to theclljarging stock. It is not necessary to employ pure olefins.

Ordinarily we may effect the desulfurization operation atambienttemperatures', although the temperature may be varied overrilbroad range, for example betweenvabout 0 F. and-,about 200 Usuallythe process of the invention is con-J ducted at temperatures betweenabout 50 F. and about 100 F., for example between 'about 60 F. and about80 F.

The reaction between a hydrocarbon disulfide and a mono-olefinichydrocarbo'niis exothermic and ,rapid at about room temperature.Accordingly, dependent upon the particular temperature HFzoil ratio,disulfide concentration in the oil,fintirnacy of contacting, etc.,tlileriod of contacting between the hydrogen fluoride, olefin anddisulfide may be varied fromfabout 1 minute or even less to about 10minutes 1,

Suilicient pressure is maintained in the contacting-zone and inthezoneallwhere the acid phase is separated from the desulfurizedhydrocarbon 'charging Vstock to maintain at least a substantialproportion of the VVhydrogen fluoride and A'charging stock in the liquidphase. 'Ordinarily pressures between about 0y and about 200 p; s. ijg.are suitab1e,ie. g. a pressure of about 25 or 50 pgs. i. g. i i

Thecontacting and acid separation equipment heretofore` employed inI-IF-catalyzed alkylation of isoparailins with olens can be employed inthe-practice of this invention. Thus the charging stock, hydrogenfluoride and added olefin (if any) can be passed through a coil, whichmay be provided with baffles to induce mixing, and thence into a gravitysettler or centrifuge; the `coil may be immersed in a heat transfer bathto' provide for removal of the heat generated in the reaction and tomaintain the reaction temperature within desired limits. In another modeof operation, the charging stock, hydrogen fluoride and added olefin maybe pumped through orifice mixers, venturis' 'or' other mixing devicesandthence into a gravity settler or centrifuge for effecting separationof desulfurized hydrocarbon and an acidv phase containing extractedsulfur compounds. Other equipment and process flows will be specificallydescribed in conjunction with the accompanying figures. In the specificembodiment of our invention schematically illustrated in Figure 1, thecon'- tactor I0 is provided with a heat transfer jacket Il through whicha cooling fluid is circulated during the contacting to remove heatgenerated bythe reaction, thereby maintaining the contacting temperaturewithin the desired limits. In order to effect intimate mixing, contactorI0 is provided with motor-driven stirring paddles I2.

The hydrocarbon charging stock containing hydrocarbon disulfldes, e. g.,a sweetened, straight run" gasoline containing substantially no oleflnichydrocarbons is passed into the contactor through valved line I3. Amono-olenic hydrocarbon, forV example a refinery ethylene, propylene orbutylene fraction can be charged into the contactor -through valved lineI4. If desired part or all of the olefinic material may be premixed withthe hydrocarbon charging stock so that a blend of olefln and hydrocarboncharging stock will be charged to the contactor through line I3. It ispreferred to charge an amount of olefin substantially equimolar with theamount of hydrocarbon disulfide contained in the hydrocarbon chargingstock in order to achieve thoroughgoing desulfurization of said stock.However, it will be appreciated that less than an equimolar amount ofolen may be employed in any one contacting stage and that a number ofcontacting stages may be employedwith the addition of olefin in `eachstagel Ordinarilyit is undesirable to add more than an equal amount ofolen to the charging stock, unless it is desired also to effect olenpolymerization to increase the yield of hydrocarbon" product from thedesulfurization process. Also, it may be desirable to add more than anequimolar amount of olefin, based upon the amount of hydrocarbondisulde, whenit is desired to effect alkylation of aromatic hydrocarbonsor isoparaillnic hydrocarbons which may be present inthe hydrocarboncharging stock.

Fresh concentrated liquid hydrogen fluoride is charged into thecontactor from source i5 through valved line I6, e. g., in anvamountequivalent to about 20 per cent by volume based on the volume ofl`hydrocarbon charging stock. It is desirable to favoid extensive orprolonged contact of the liquid hydrogen fluoride with the olefin in theabsence lof the charging stock containing hydrocarbon fdisulfldes'sincecontact may lead to unastenerdesirable' rea'ctionsVv such? fas" olefinpolymerization accompanied. by hydrogen disproportionation", whereby theeffective concentratioxr'ofolen is appreciably reduced in thecontactirigpzone".

,.'In' contactorlf'the charging stock; vo'leiirr1and hydrogen fluorideare' agitated at a rate sucient to' cause intimate admix'ture at a-suitabletenie perature, for example about 60 F..toabout 86 Ff for a"suitable peri'od1,.'.for example' about I hour, and are thenidischargedv through valved lin'e l1 into a cooler `Iii where thetemperature of the mixture 'is adjusted to a` desirable 'value for. the?subsequent' step of separating the hydroe carbon and` acid phases.desired, additional concentrated liquid' hydrogen.' iiuoride may be'added-to the mixture in line l1" through' valved line 191' From coolert8 themixture' passes Vthroug'hilline zfixintoa sett1er'2l whereindesulfurize'd hydro# carbons arevsepar'ated from a liqu'idhydrogenlfluoride phasecontaining sulfur compounds. though' thesettleris depictedas a gravity settler, it-:will be appreciated that a` centrifuge couldbeemployed instead. If desired,- thesettler may be provided with packingto serve as an aid to'strati-- ication'.: Suitable packing materialscomprise shapedfragments of carbon, coppen'Monel' metal, carbon steeland certainl magnesium alloys con tain-ing'minor amounts of aluminum andstill smaller amounts of otheralloyingelements such as zincformanganese'. (Dowmetals). The-settler' isequippe'd with an overheadvalvedVent line 22 through which 'light gases maybe released to adjust thepressure to a desired value. Suitable operatingl conditions for thesettlercomprise" a n is vaporized, optionally at pressures below atrnfosphericand/or with the aidot stripping gases asmethaneg.ethane-,fpropane; bu-tane, permane,-V etc: From theY stripping zonethehydrocarbon passes throughl valved line 275y tot storage or. tot suchulterior treatment,- e. g.r, neutralizationfvas.may be desired.

' Residual hydrogen' fluoridernay be .removed from the hydrocarbon oilby washing-with alka-f linemateria-ls,` e.v g; caustic'soda; by ypassageover metal uori'des, e. g., sodium'or potassium uorid-es orhydroiuorides; by passage over'adsorp'a tivematerials such as-activatedalumina, chrom; iuinr 0Xicle---alurnina,v silica gel;- activated-carbonand the like.

When unsaturated hydrocarbon charging stocks are employed, alkyl'uoridesare-usually formed therein. The alkyl uoridesf have detrimentalEef.-` tectsoni the octane number of hydrocarbon fuels and shouldbel'removed therefrom. number. of methods are amai-labileiordeluorination, includ;- ing high temperature treatmentwith bauxiteand thelike..

.f "Eher 'acid :phase `isf discharged from' the settler through .valvedline 28, whence partV or all thereof may be recycled to 'contactor 'Idthrough Valved liner` 2l, heat exchangerv 28% inl which its tempera ture'is brought tothe desired value for the con: tac'ting operation', andvalved linelt'. It is desirable to pa'ss` atleast a partr of the acid:phase fromthe settlerrthrough Vals/,fed line; 29' and heaterY filito'a;- Zorre Ltlief'hydrogeir fi'uoridezand sulfur compounds in solution`therein are' sepafr rated 'f v3;' v`i Whei the recovery ofhydrogenffiuorideais'une important andthe' -principal object is'tdseparate the' sulfur compounds, the` acid may bel diluted with wateronneutrahZedQwhereupon the-suitorcompoundanotably di-thioethers,separate' as an immi'scible liquid phase which may be washed withWater'and.fractionate-dintoclose lboiling fractions which'fmayhaveindustrial value; Ordinarily 'it isdesirable to .separatehydrogenfluoride in suit-I able formz-forireuse irrzthe contacting.;operatioi'ii It is; therefore', desirable tosubiecttheacid phasefrottis-the ,settler .tof aA fractionation operation.l This may beeffected in` fractionator 3'I Inor'der to aidthe vaporizationandwithdrawal oi hydrogen. fluoride-zr," a; stripping gas," whiclfr mayyform a/minimum-yboiling` azeotrope withchydro-gen flu--r oridev mayfbe:introduced intol the. lower portion ofitheiractionatorthrouglr Valvedline .32; Suita abile"-stripping` gases include' methaner-ethane-,propane, butanestandf pentanesi` If desired frac'a tionator 3! may beoperated at a subatmospheric pressure- V Hydrogenrluoride isvaporizedfin: the

tractionator and. passes i overhead through v-valved line-33 forcondensation and reuse-in contacter l0.

The higher boilingsulfur compounds are withdrawir from the fractionatorthrough-valved line tdi 'Iv-hey may be freed lfromv traces oi acid-by`washing withalkaliesf-andwater or by passage over materials capableofadsorbing orcombi-ning chemically with: hydrogen fluoride Figure-f2illustrates another embodimentzoi our invention wherein counterowcontacting of. the" hydrocarbon charging stock with liquid hydrogenfluoride and separation of a desulfurized hydrocarbon phase and an; acidphase enriched in sulfurzc'ompoun'dsware effected in one tower. Desuldrfurizatioir tower HI8 is provided with contacting means iol', forexample shaped-:packing vmaterials such as fragments of carbon, copper,-Monel metal, carbon steel, magnesium alloys, etc.A Heat" exchange coilsm2 -are provided in the contacting section ofthe tower to aid in'controlling the temperature.; Hydrogen uori'de is admitted into thetower from Ya source'such as storage tan-ky H13; valvedline l Slt andline |05, passing into the upper portion of the contacting zone inthetower, whence it passes-.downwardly'to-the lower end. of the-tower.The-hydrocarboncharging stock containingV hydrocarbon Adisuliidesispassed into the lower portion toi the contacting zone inthe towerthroughvalvedli-ne' I o5 and rises thro-ugh the contactingr zone`against the -counterflow oi' liquid hydrogen uor-ide. The desiredamount 'oi olefin is added i to v the hydrocarbon charging stockthroughpva-lved line i'l, The upper end oi the' tower, above thecontacting zone-serves1asasettling'zonefor. the desuliurized or partly'desul furized hydrocarbon charging stock'which-is'withA drawn .therefromthrough' valv'ed line mit; whence it may 'be withdrawn throughl'iydrogenfluoridestripping zone tti-Siandidischarged from ther systemthrough.lineflfMl.: It isusually desirable to 'neue tralize traces ot,hydrogen uoride which Iiiay` be containedirr the?y oilfleaving thesystem through 1in@ Y Y Partf of the 'partly' desulfurized hydrocarbonstock may be recycled tothe vcontacting zone in tower I through-valvedline i i I, Vheat exchanger I IEfand valvedlined-llt.AA TheV acidcontaining' dis# solveds'ulfur compoundssettles into' the lowermostportion of tower it whence: it iswi-thdrawn through .valvedline H3; andmay: be recycled to diaria? the contacting zone through'pum'p'fl I4,valved line |,I 5, cooler IIB and line |05. It is, however, desirable topass part or all of the-acidy phaseI from tower through valved line II1and heater II'8 into a fractionator': I I9." lIn the fractionator,hydrogen fluoride is vaporized and passed overhead through Valved line|20, whence at least a .portion of the hydrogen iluoride vapors mayberemoved from the 'system' through valved line I2| preferably part or allof l; the `hydrogen c uoride vapors are passed through valved line"V|22r and condenser |23 foi1 recycle'throughlline A,|05 tothedesulfurization tower |00. Toaid in the v'aporiation of hydrogenfluoride in the fractionator, a stripping gas is passed through valvedline |24 and/or the fractionator may be operated at a subatmosphericpressure. Sulfurcompounds are withdrawn from fractionator ||9 throughvalved line |25. Gases which may accumulate in the system may be removedfrom the desulfuri'zation Vtower |00 through a valved vent line |26.

The following examples are introduced in order to illustrate but notunduly to limit the scope o the process of this invention.

Example 1 A solution of n-octyl disulde and n-heptane was preparedcontaining 1.50 weight per cent of sulfur. This solution was agitatedfor 1 hour at room temperature with 200 cc. of commercial liquid,substantially anhydrous hydrogen fluoride per liter of the solution,,after which agitation y was discontinued and the contacting mixture wasallowed to separate by gravity into an upper hydrocarbon phase and alower acid phase. Sulfur analyses of the phases indicated that only 9 vweight per cent desulfurization of the n-heptane had occurred. Underotherwise identical operating conditions but with the addition of 1 molof diisobutylene per mol of disulde contained in the n-heptane, 95 percent desulfurization of the n-heptane occurred. Since diisobutylenedepolymerizes readily, one mol thereof can be considered as thesubstantial equivalent of two mols of isobutylene. It is apparent thatthe disulfide reacts with the olefin to produce a sulfur compound whichis far more soluble in liquid hydrogen fluoride than n-octyl disulfide,which under the conditions lof this experiment was relatively insolublein liquid hydrogen fluoride. It appears that the HF-soluble sulfurcompound which is produced when an olefin is added is a di-thioether.

Example 2 indicated that 99 weight per cent desulfurization of then-heptane had occurred. In the absence of an added olefindesulfurization to the extent of only about 60 weight per cent could beexpected.

Although we have speciiically described the desulflurization ofhydrocarbon oils containing hydrocarbon disul-des by reaction andextraction with liquid hydrogen iluoride and a, mono-olenic hydrocarbon,it will beappreciated that other organic compounds containing olefnicunsaturation .might be ,used instead. Although we have emphasized thereactions of ,hydrocarbon disulfides with olens in the presence ofliquid hydrogen fluoride as. a catalyst and solvent for the product, itis appreciated thatthe liquid hydrogen-fluoride may exert more or lesssolvent` capacityl for other sulfur compounds which may b e presentiinthechydrocarbon chargingstock, .for

example thiophenes, Athiophanes or, thioethers.

Mercaptans react with olefins in the presence of liquid hydrogen uorideas a catalyst-solvent to form thioethers which are extracted by thehydrogen fluoride from the hydrocarbon charging stock.l Thioethers arefar more soluble in liquid hydrogen fluoride than the correspondingmer-Captaris...` i

The general reaction of organic disulides with-: olenic hydrocarbons inthe presence of chemical compounds'which are acidic chemiicalcondensation catalysts to effect the preparation of dithioethers isclaimed in applicants copending application for U. S. Letters Patent,Serial No. 755,456, filed of even date herewith.

Having thus described our invention, what we claim is:

1. A process which comprises sweetening a mercaptan-containinghydrocarbon oil to produce a, hydrocarbon oil containing disuldes,adding an olenic hydrocarbon to the sweetened oil in an amountsufficient to increase the molar ratio of olenic hydrocarbons todisuldes to at least one, contacting the sweetened hydrocarbon oil inthe presence of said oleflnic hydrocarbon with liquid hydrogen fluoridein quantity sucient at least to form a distinct liquid phase at aternperature between about 0 F. and Vabout 200 F. under a pressuresufficient to maintain the liquid phase, thereby effecting chemicalreaction between said disuldes and said olenic hydrocarbon to produce ahydrogen fluoride-soluble sulfur-containing reaction prod'uct, andthereafter separating a hydrocarbon oil of reduced sulfur content and aliquid hydrogen fluoride solution of said sulfur-containing reactionproduct from the mixture produced in the contacting operation.

2. A process which comprises sweetening a cracked sour hydrocarbon oil,adjusting the olefinzdisulfide molar ratio of said oil to about one andcontacting said oil with liquid hydrogen uoride in quantity sufficientat least to form a distinct liquid phase, thereby effecting chemicalreaction between said disulfide and said olefin to form a hydrogenuoride-soluble sulfur-containing reaction product, and thereafterseparating a hydrocarbon oil of reduced sulfur and olefin content and aliquid hydrogen fluoride solution of said sulfur-containing reactionproduct from the mixture produced in the contacting operation.

3. In a multi-stage process of removing a hydrocarbon disulfidecontained in a hydrocarbon oil, the steps of contacting said hydrocarbonoil in a plurality of stages with concentrated hydrogen uoride inquantity sufficient at least to form a distinct liquid phase with anadded olefinic hydrocarbon in an amount such that the olefinichydroearbonsdisulde molar ratio is less than one in any stage but thetotal olefinic hydrocarbomdisulde molar ratio in all the stages isatleast one, effecting chemical reaction between said disulfide and saidolefinic hydrocarbon in each stage to form a hydrogen fluoride-solublesulfur-containing reaction product, and withdrawing from the process ahydrocarbon oil substantially free of said hydrocarbon disulfide and

1. A PROCESS WHICH COMPRISES SWEETENING A MERCAPTAN-CONTAININGHYDROCARBON OIL TO PRODUCE A HYDROCARBON OIL CONTAINING DISULFIDES,ADDING AN OLEFINIC HYDROCARBON TO THE SWEETENED OIL IN AN AMOUNTSUFFICIENT TO INCREASE THE MOLAR RATIO OF OLEFINIC HYDROCARBONS TODISULFIDES TO AT LEAST ONE, CONTACTING THE SWEETENED HYDROCARBON OIL INTHE PRESENCE OF SAID OLEFINIC HYDROCARBON WITH LIQUID HYDROGEN FLUORIDEIN QUANTITY SUFFICIENT AT LEAST TO FORM A DISTINCT LIQUID PHASE AT ATEMPERATURE BETWEEN ABOUT 0*F. AND ABOUT 200F. UNDER A PRESSURESUFFICIENT TO MAINTAIN THE LIQUID PHASE, THEREBY EFFECTING CHEMICALREACTION BETWEEN SAID DISULFIDES AND SAID OLEFINIC HYDROCARBON TOPRODUCE A HYDROGEN FLUORIDE-SOLUBLE SULFUR-CONTAINING REACTION PRODUCT,AND THEREAFTER SEPARATING A HYDROCARBON OIL OF REDUCED SULFUR CONTENTAND A LIQUID HYDROGEN FLUORIDE SOLUTION OF SAID SULFUR-CONTAININGREACTION PRODUCT FROM THE MIXTURE PRODUCED IN THE CONTRACTING OPERATION.